A clean and effective supercritical carbon dioxide method for the host–guest synthesis and encapsulation of photoactive molecules in nanoporous matrices

Abstract

The present work is concerned with host–guest processes in the micro- and mesoporous restricted spaces provided by silica aerogels and aluminosilicates. A supercritical carbon dioxide ship-in-a-bottle approach was used for the synthesis of photoactive molecules (triphenylpyrylium and dimethoxyltrityl cations) inside these nanoporous matrices. The resulting hybrid nanocomposites can act as stable and recoverable heterogeneous photocatalysts, having obvious advantages with respect to the more easily degraded organic cations frequently used in homogeneous catalysis. Two aspects of green chemistry are combined in this study to produce nanoporous materials loaded with cationic photosensitizers: (i) the use of supercritical carbon dioxide as a reaction medium in one-pot and as a zero waste technology, and (ii) the use of transparent high surface area nanoporous supports that are expected to be more effective for the target photoactive applications than traditional opaque microporous matrices.